From 09cc9ab63d0f50d107a03390b70dfdfbfe6aa363 Mon Sep 17 00:00:00 2001
From: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Date: Wed, 16 Jun 2004 10:44:26 +0000
Subject: [PATCH] Implement 3 new functions: 	- g_lcm() - calculates Least
 Common Multiple of two given values, 		it is helpful when we need to
 find sector size for provider 		which is based on disks with different
 sector size; 	- g_get_mediasize() - returns media size of given provider; 
 - g_get_sectorsize() - returns sector size of given provider; Those function
 aren't used now, but are used by geom_mirror which will be committed soon.

---
 sbin/geom/misc/subr.c | 76 ++++++++++++++++++++++++++++++++++++++++---
 sbin/geom/misc/subr.h |  5 +++
 2 files changed, 77 insertions(+), 4 deletions(-)

diff --git a/sbin/geom/misc/subr.c b/sbin/geom/misc/subr.c
index 9d72e3483442..ae639b7a9017 100644
--- a/sbin/geom/misc/subr.c
+++ b/sbin/geom/misc/subr.c
@@ -69,6 +69,70 @@ pathgen(const char *name, char *path, size_t size)
 		strlcpy(path, name, size);
 }
 
+/*
+ * Greatest Common Divisor.
+ */
+static unsigned
+gcd(unsigned a, unsigned b)
+{
+	u_int c;
+
+	while (b != 0) {
+		c = a;
+		a = b;
+		b = (c % b);
+	}
+	return (a);
+}
+
+/*
+ * Least Common Multiple.
+ */
+unsigned
+g_lcm(unsigned a, unsigned b)
+{
+
+	return ((a * b) / gcd(a, b));
+}
+
+off_t
+g_get_mediasize(const char *name)
+{
+	char path[MAXPATHLEN];
+	off_t mediasize;
+	int fd;
+
+	pathgen(name, path, sizeof(path));
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return (0);
+	if (ioctl(fd, DIOCGMEDIASIZE, &mediasize) < 0) {
+		close(fd);
+		return (0);
+	}
+	close(fd);
+	return (mediasize);
+}
+
+unsigned
+g_get_sectorsize(const char *name)
+{
+	char path[MAXPATHLEN];
+	unsigned sectorsize;
+	int fd;
+
+	pathgen(name, path, sizeof(path));
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return (0);
+	if (ioctl(fd, DIOCGSECTORSIZE, &sectorsize) < 0) {
+		close(fd);
+		return (0);
+	}
+	close(fd);
+	return (sectorsize);
+}
+
 int
 g_metadata_store(const char *name, u_char *md, size_t size)
 {
@@ -85,11 +149,13 @@ g_metadata_store(const char *name, u_char *md, size_t size)
 	fd = open(path, O_WRONLY);
 	if (fd == -1)
 		return (errno);
-	if (ioctl(fd, DIOCGMEDIASIZE, &mediasize) < 0) {
+	mediasize = g_get_mediasize(name);
+	if (mediasize == 0) {
 		error = errno;
 		goto out;
 	}
-	if (ioctl(fd, DIOCGSECTORSIZE, &sectorsize) < 0) {
+	sectorsize = g_get_sectorsize(name);
+	if (sectorsize == 0) {
 		error = errno;
 		goto out;
 	}
@@ -129,11 +195,13 @@ g_metadata_clear(const char *name, const char *magic)
 	fd = open(path, O_RDWR);
 	if (fd == -1)
 		return (errno);
-	if (ioctl(fd, DIOCGMEDIASIZE, &mediasize) < 0) {
+	mediasize = g_get_mediasize(name);
+	if (mediasize == 0) {
 		error = errno;
 		goto out;
 	}
-	if (ioctl(fd, DIOCGSECTORSIZE, &sectorsize) < 0) {
+	sectorsize = g_get_sectorsize(name);
+	if (sectorsize == 0) {
 		error = errno;
 		goto out;
 	}
diff --git a/sbin/geom/misc/subr.h b/sbin/geom/misc/subr.h
index 487f3db5ceb8..f88af01bddb2 100644
--- a/sbin/geom/misc/subr.h
+++ b/sbin/geom/misc/subr.h
@@ -28,6 +28,11 @@
 
 #ifndef _SUBR_H_
 #define	_SUBR_H_
+unsigned g_lcm(unsigned a, unsigned b);
+
+off_t g_get_mediasize(const char *name);
+unsigned g_get_sectorsize(const char *name);
+
 int g_metadata_store(const char *name, u_char *md, size_t size);
 int g_metadata_clear(const char *name, const char *magic);